1. Field of the Invention
The present invention relates to a process for converting penicillin sulfoxides to desacetoxy cephalosporanic acids. More particularly, the present invention relates to a process for producing 7-substituted aminodesacetoxy cephalosporanic acids represented by the formula (III) ##SPC3##
wherein R.sub.1 is an acyl group, and R.sub.2 is alkyl, aryl or arylalkyl which comprises heating penicillin sulfoxides represented by the formula (I), ##SPC4##
wherein R.sub.1 and R.sub.2 are the same as defined above, at 50.degree. to 160.degree.C in an inert organic solvent in the presence of a sulfonate represented by the formula (II), ##EQU2## wherein A is ##EQU3## S - R.sub.6 or ##EQU4## and R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are lower alkyl, phenyl, benzyl or phenethyl, R.sub.7 is 1-12C alkyl, phenyl, 1-12C alkyl-substituted phenyl, naphthyl, 1-12C alkyl-substituted naphthyl, halogen-substituted phenyl, and wherein when A is ##EQU5## R.sub.3, R.sub.4 and R.sub.5 may form a heterocyclic ring together with the nitrogen atom, and when A is S--R.sub.6, R.sub.3 and R.sub.4 may form a heterocyclic 4-5C polymethylene ring or R.sub.6 and R.sub.7 may bond to form a polymethylene link.
2. Description of the Prior Art
The desacetoxy cephalosporanic acids represented by the formula (III) have antibacterial activity in themselves and are utilized in medicinal applications. However, the cephalosporanic acids are also useful as intermediates for the syntheses of other cephalosporin compounds having high antibacterial activity.
U.S. Pat. No. 3,275,626 discloses the conversion of 6-amino-penicillin sulfoxides to desacetoxy cephalosporanic acids upon heating at approximately 80.degree. to 175.degree.C under acidic conditions. This reaction is promoted by acetic anhydride or p-toluenesulfonic acid. However, in this process the reaction is conducted under severe conditions by heating the acids in acidic media. Thus, side reaction tends to readily occur resulting in low yields of product and poor economy.
A need, therefore, continues to exist for a process for converting penicillin sulfoxides in high yield and selectivity to aminodesacetoxy cephalosporanic acids.